Sofrito: Place onions in sauté pan at medium-low heat. Add garlic a few minutes later. Once the onions are translucent (around 10 minutes), add the finely chopped peppers. Add the aji dulce, if you are using it. Simmer and let the flavors seep, until the vegetables are tender and aromatic. Separate the finished sofrito. You will use about half in cooking the beans and the other half for cooking the meat. Shredded beef: Place the water in the pressure cooker and start to simmer. Add the garlic, green pepper, onion, meat concentrate, and salt and simmer a few minutes longer. Then, place the meat in the pressure cooker and cover. Once it starts to boil, you will cook for one hour. If you are using a regular stock pot, cooking can take several hours. You know the meat is ready when you can shred it with a fork. Remove the beef from the pot, reserving one cup of the broth. Shred the meat with two forks and place in a heavy duty or cast-iron pan with a tablespoon of meat concentrate. Add one-half of the reserved sofrito. Pour one cup of reserved broth over this. Add Worcestershire sauce. Simmer at medium heat until the liquid has evaporated. Beans: Place the beans in a pan, along with half of the sofrito. Add about a 1 inch square of panela to the sofrito you reserved for the beans. Stir in cumin and bay leaf. Continue to stir until the panela is dissolved. Heat through a few minutes longer, stirring occasionally. Plantains: You can fry plantains, or use frozen ones to expedite the cooking. Cut the frozen plantains unto squares. Place butter on a frying pan at medium heat, along with oil. Add panela and stir so that it dissolves. Gently add the chopped plantains and stir in with the dissolving panela. Cook on medium heat, stirring constantly. Add salt. Turn off heat and sprinkle cinnamon over plantains. Dough: Prepare dough with about one cup water and to about one cup Harina Pan. Add one tablespoon sugar. Use your hands to incorporate the water into the harina. The dough should be moist and easy to form into a ball. It should not be gloppy or sticky. Meanwhile, heat about ½ cup of grapeseed or corn oil in a non-stick frying pan. Grab a clump of dough and form into a ball. Press the dough into a flat circle in the press, about 2 to 2 ½ inches in diameter. Place a ½ teaspoon of each of the three fillings: beans, meat, and plantains in the center. Use the plastic wrap to fold the empanada in half. Gently press the sides with fingers. Seal with a fork, again gently. Test the oil with a small ball of dough. If it sizzles and cooks, the oil is ready. Place empanada in the oil. Carefully spoon some oil onto the top of the empanada to speed the cooking of the top as well. Once the bottom is golden brown, carefully turn the empanada over. Once it is golden brown all over, place the empanada on a plate lined with paper towels. You can keep them for up to 2 hours, but it is best to place them in an oven heated to 200 degrees to avoid sogginess.